IpM 


U^ 


Issued  January  17, 1917. 

AWAII  AGRICULTURAL  EXPERIMENT  STATION, 

J.   M.   WESTGATE,  Agronomist  in  Charge. 


Bulletin  No.  42 


COMPOSITION  OF  HAWAIIAN  SOIL 
PARTICLES. 


jm  ofT~~p — 


BY 


WM.  T.  McGEORGE, 

Former  Chemist,  Hawaii  Agricultural  Experiment  Station. 


UNDER   THE    SUPERVISION    OP 

STATES  RELATIONS  SERVICE, 
Office  of  Experiment  Stations, 

U.    S.    DEPARTMENT    OF  AGRICULTURE. 


WASHINGTON: 
GOVERNMENT   PRINTING  OFFICE. 


Issued  January  17,  1917. 

HAWAII  AGRICULTURAL  EXPERIMENT  STATION, 

J.   M.  WESTGATE,  Agronomist  in  Charge. 


Bulletin  No.  42. 


COMPOSITION  OF  HAWAIIAN  SOIL 
PARTICLES. 


BY 


WM.  T.  McGEORGE, 

Former  Chemist,  Hawaii  Agricultural  Experiment  Station. 


UNDER  THE    SUPERVISION   OF 

STATES  RELATIONS  SERVICE, 
Office  of  Experiment  Stations, 

U.    S.    DEPARTMENT   OF  AGRICULTURE. 


WASHINGTON: 

GOVERNMENT   PRINTING  OFFICE. 

1917 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION,  HONOLULU. 

[Under  the  supervision  of  A.  C.  True,  Director  of  the  States  Relations  Service,  United 
States  Department  of  Agriculture.] 

E.  W.  Allen,  Chief  of  Office  of  Experiment  Stations. 

Waltee  H.  Evans,  Chief  of  Division  of  Insular  Stations,  Office  of  Experiment 

Stations. 

STATION  STAFF. 

J.  M.  Westgate,  Agronomist  in  Charge. 

J.  Edgar  Higgins,  Horticulturist. 

M.  O.  Johnson,1  Chemist. 

F.  G.  Kratjss,  Superintendent  of  Extension  Work. 

J.  B.  Thompson,  Assistant  Agronomist,  in  Charge  of  Glenwood  Substation. 

Alice  R.  Thompson,  Assistant  Chemist. 

V.  S.  Holt,  Assistant  Horticulturist. 

C.  A.  Sahr,  Assistant  Agronomist. 

A.  T.  Longley,  In  Charge  of  Cooperative  Marketing  Investigations. 


LETTER  OF  TRANSMITTAL 


Hawaii  Agricultural  Experiment  Station. 

Honolulu,  Hawaii,  December  14,  1915. 
Sir  :  I  have  the  honor  to  submit  herewith,  and  recommend  for  publication  as 
Bulletin  No.  42  of  the  Hawaii  Agricultural  Experiment  Station,  a  manuscript 
entitled  "The  Composition  of  Hawaiian  Soil  Particles,"  by  Wm.  T.  McGeorge, 
formerly  chemist  of  this  station.  The  variations  in  Hawaiian  soils  as  compared 
with  the  soils  of  the  mainland  of  the  United  States  are  so  great  and  unusual 
as  to  make  it  of  economic  importance  to  determine  as  many  as  possible  of  the 
fundamental  causes  of  the  variations.  As  pointed  out  in  the  accompanying 
manuscript,  the  size  of  the  particles  of  different  Hawaiian  soils  bears  a  distinct 
relation  to  their  composition. 

Respectfully,  J.  M.  Westgate, 

Agronomist  in  Charge. 
Dr.  A.  C.  True, 

Director  States  Relations  Service, 

U.  S.  Department  of  Agriculture,  Washington,  D.  C. 

Publication  recommended. 
A.  C.  True,  Director. 

Publication  authorized. 

D.  F.  Houston,  Secretary  of  Agriculture. 

1  Appointed  July  25,  1915,  to  succeed  Wm.  T.  McGeorge,  transferred  to  U.  S.  Depart- 
ment of  Agriculture,  Bureau  of  Chemistry. 

(2) 


COMPOSITION  OF  HAWAIIAN  SOIL  PARTICLES. 


CONTENTS. 


Page. 

Introduction 1 

Origin  of  Hawaiian  soils 1 

Changes  during  disintegration 5 

Selection  of  soil  types 6 


Page. 

Composition  of  the  soil  particles 8 

Properties  of  the  soil  particles 10 

Conclusions 12 


INTRODUCTION. 

One  of  the  primary  characteristics  of  Hawaiian  soils  is  the  wide 
diversity  of  types  which  makes  difficult  their  classification  according 
to  the  usual  methods  employed  in  soil  surveys.  A  wide  variation  in 
chemical  composition,  as  well  as  in  physical  properties,  is  found 
within  very  short  distances.  During  a  recent  investigation  in  this 
laboratory  upon  the  determination  of  humus,  the  character  of  the 
clay  in  Hawaiian  soils,  as  regards  certain  of  its  properties,  was  found 
to  be  radically  different  from  that  in  mainland  soils.  Chief  among 
these  abnormal  properties  is  the  incomplete  coagulation  when  coag- 
ulants are  added.  This  is  especially  true  in  case  of  addition  of 
ammonium  carbonate,  which  has  been  successfully  used  on  mainland 
soils  for  the  coagulation  of  clay  in  humus  extracts. 

This  peculiarity  of  the  clay  has  led  to  a  study  of  the  composition 
of  the  coagulable  and  noncoagulable  grains  and  a  further  investiga- 
tion upon  the  composition  of  the  clay,  fine  silt,  silt,  fine  sand,  and 
coarse  sand  separates  in  the  important  Hawaiian  types  of  soil  differ- 
ing in  color,  chemical  composition,  and  physical  properties. 

ORIGIN   OF  HAWAIIAN   SOILS. 

In  order  to  understand  clearly  the  composition  of  the  soil  separates, 
it  is  necessary  to  know  something  of  the  origin  of  Hawaiian  soils, 
at  least  the  three  possible  sources  from  which  they  may  be  derived, 
namely,  volcanic  lava,  volcanic  ash,  and  coral  sand.  As,  with  the 
exception  of  small  areas  near  the  sea.  coral  sand  need  not  be  con- 
sidered a-  a  factor  in  soil  format  ion  in  the  islands,  and  as  there  is 
-16  (3) 


little  material  difference  in  the  composition  of  the  lava  and  ash,  the 
source  of  Hawaiian  soils  narrows  down  to  volcanic  basalts  of  a  more 
or  less  uniform  composition.  Analyses  of  lava,  volcanic  ash,  and 
coral  sand  are  given  in  the  following  table : 

Analyses  of  lava,  volcanic  ash,  and  coral  sand. 


Constituents. 


Lava. 


From  Oahu. 


Sample 
B. 


Sample 
E. 


Sample 
F. 


From  Hawaii. 


Sample 
No.  501. 


Sample 
No.  502. 


Sample 
No.  503. 


Silica  (Si02) 

Alumina  (AI2O3) 

Ferric  oxid  (Fe203) 

Ferrous  oxid  (FeO) 

Manganese  oxid  (M^O^ 

Lime(CaO) 

Magnesia  (MgO) 

Potash(K20) 

Soda(Na20) 

Sulphur  trioxid  (S03) 

Phosphorus  pentoxid  (P2O5) 

Titanic  oxid  (Ti  02) 

Moisture 


Per  cent. 
52.45 
11.49 
3.66 
6.90 

.36 
10.32 
5.81 

.89 
2.44 

.20 

.38 
4.07 
1.02 


Per  cent. 

52.15 

12.57 

3.36 

7.07 

.50 

8.54 

6.51 

.84 

2.64 

.61 

.28 

4.07 

.94 


Per  cent. 

51.  98 

15.85 

2.90 

6.84 

.92 

9.57 

5.61 

.97 

2.70 

.51 

.22 

1.50 

1.04 


Per  cent. 

52.24 

16.00 

3.73 

5.89 

.68 

9.54 

5.90 

.86 

2.65 

.53 

.11 

1.50 

.54 


Per  cent. 

48.88 

12.84 

.30 

8.52 

.31 

9.55 

10.29 

.75 

1.44 

.33 

.21 

2.54 

4.45 


Per  cent. 

48.55 

14.83 

2.44 

6.07 

.66 

8.56 

14.22 

.72 

1.56 

.19 

.22 

2.15 

.09 


Per  cent. 

52.07 

14.12 

2.64 

-7.01 

.72 

10.71 

7.51 

.74 

1.93 

.35 

.24 

2.42 

0 


Constituents. 


Lava. 


From  II  awaii. 


Sample 

Sample 

No.  504. 

No.  505. 

Per  cent. 

Per  cent. 

51.25 

49.94 

14.36 

14.42 

3.30 

1.04 

6.43 

8.01 

.44 

.20 

10.65 

11.59 

9.12 

9.08 

.64 

.80 

1.96 

1.79 

.33 

.33 

.17 

.26 

2.35 

2.86 

0 

0 

Sample 
No.  519. 


Volcanic  ash. 


From  Maui. 


Sample 
No.  506. 


Sample 
No.  507. 


From 
Oahu. 


Sample 
No.  132. 


Coral 
sand. 


From 

Oahu. 


Sample 
No.  227. 


Silica  (Si02) 

Alumina  (A1203) 

Ferric  oxid  (Fe203) 

Ferrous  oxid  (FeO) 

Manganese  oxid  (Mn204)  — 

Lime(CaO) 

Magnesia  (MgO) 

Potash(K20) , 

Soda  (Na20; 

Sulphur  trioxid  (S03) 

Phosphorus  pentoxid  (P205) 

Titanic  oxid  (Ti02) 

Moisture 


Per  cent. 

50.69 

15.62 

.49 

4.65 

.28 

11.14 

6.55 

.90 

2.56 

.78 

.34 

5.53 

.10 


Per  cent. 
45.54 
17.42 
8.60 


Per  cent. 
46.98 
16.62 
7.08 


1.17 

8.90 

6.14 

1.82 

2.92 

.36 

.63 

6.00 

.74 


.18 
7.16 
5.58 
1.32 
2.62 
.46 
.59 
6.60 
1.55 


Per  cent. 

36.82 

18.08 

10.40 

4.32 

.46 

9.52 

.54 

5.62 

10.20 

.18 

.70 

5.50 

.09 


Per 


cent. 

2.60 

0 

.21 


0 

92.40 

2.90 

.31 

.46 

.55 

.21 

j0 


Samples  A,  B,  E,  and  F  are  from  unaltered  lava  in  the  Wahiawa 
district  of  Oahu.  Nos.  501  to  505,  inclusive,  are  from  the  different 
flows  of  Mauna  Loa  on  the  Island  of  Hawaii.  No.  501  was  taken 
from  the  flow  of  1823  and  had  undergone  a  slight  decomposition; 
No.  502  was  taken  from  the  flow  of  1868  and  showed  slight  changes 
in  appearance,  due  probably  to  hydration  and  leaching;  No.  503 
came  from  the  flow  of  1883;  No.  504  from  that  of  1907;  and  No. 
505  from  the  small  overflow  of  1910  at  Kilauea.     No.  519  is  a  sample 


of  "  Pele's  Hair."  a  term  that  is  used  to  describe  the  hair-like  threads 
of  lava  formed  at  Kilauea  by  explosions  in  the  molten  lava.  Nos. 
506  and  507  are  black  ash  from  Haleakala  Crater  on  Maui,  while 
Xo.  132  is  a  sample  of  black  ash  from  Oahu  which  had  been  sub- 
merged at  one  time  by  the  sea.  Xo.  227  is  a  sample  of  coral  sand  from 
the  island  of  Oahu.  There  is  a  marked  similarity  in  the  composition 
of  the  lavas  from  both  islands.  xV  slight  variation  in  the  content 
of  soda  and  magnesia  is  the  only  perceptible  difference.  The  same 
is  also  true  of  the  volcanic  ash  from  different  sources,  except  that 
potash  should  be  included  as  one  of  the  variable  constituents.  The 
coral  sand  contains  92.4  per  cent  of  carbonate  of  lime.  The  impor- 
tant silicates  occurring  in  the  lavas  include  the  pyroxenes,  amphi- 
boles,  and  soda-lime  feldspars,  while  the  ash  contains  more  or  less 
magnetic  iron  oxid. 

The  primary  agent  of  disintegration  in  Hawaii  is  weathering. 
However,  the  climatic  factors  influencing  decomposition  vary  so 
widely  even  in  adjacent  districts  that  the  soils  formed  are  far  from 
uniform  in  composition  or  properties.  Eainfall  varies  from  a  frac- 
tion of  an  inch  to  over  200  inches  per  annum,  hence  there  are  humid, 
dry,  and  even  arid  districts.  Temperature  changes,  while  not  rapid, 
vary  from  the  tropical  heat  to  temperate  conditions,  with  snow  at 
times  in  the  higher  mountains.  Again  there  must  be  included  as 
an  agent  of  disintegration  the  trade  winds  which  play  no  small  part 
in  the  transportation  of  soil  grains.  The  process  of  lava  disintegra- 
tion is  generally  referred  to  as  laterisation,  but  in  certain  of  the 
districts  submersion  by  the  sea  following  their  formation  has  ma- 
terially influenced  the  disintegration  of  the  laterite  and  the  com- 
position of  the  soil. 

Since  practically  all  the  known  weathering  agents  are  concerned 
in  the  formation  of  Hawaiian  soils,  acting  either  separately  or  in 
different  combinations,  it  is  not  surprising  that  the  types  vary  so 
greatly  in  closely  situated  districts. 

CHANGES  DURING  DISINTEGRATION. 

In  a  previous  publication  of  this  station 1  analyses  are  given  show- 
ing the  effects  of  disintegration  on  the  composition  of  lava  during 
the  process  of  soil  formation.  These  analyses  are  reproduced  here 
in  order  to  show  more  clearly  the  relation  between  the  composition 
of  the  soil  particles  and  the  original  lava. 

1  Hawaii  Sta.  Bui.  2G  (1912). 


Analyses  of  lava  and  adjacent  lava  disintegration  products. 


Constituents. 


C. 

D. 

G. 

A. 

Disinte- 

B. 

Disinte- 

E. 

Disinte- 

F. 

Lava. 

gration 
products. 

Lava. 

gration 
products. 

Lava. 

gration 
products. 

Lava. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

52.45 

20.29 

52.15 

24.01 

51.98 

26.82 

52.24 

11.49 

37.97 

12.57 

36.27 

15.85 

30.13 

16.00 

3.66 

15.01 

3.36 

14.29 

2.90 

16.86 

3.73 

6.90 

3.22 

7.07 

3.31 

6.84 

3.03 

5.89 

.36 

.19 

.50 

.43 

.92 

.06 

.68 

10.32 

.33 

8.54 

.17 

9.57 

.22 

9.54 

'5.81 

.20 

6.51 

.09 

5.61 

.11 

5.90 

.89 

.25 

.84 

.24 

.97 

.46 

.86 

2.44 

.27 

2.64 

.31 

2.70 

.57 

2.65 

.20 

.78 

.61 

.49 

.51 

.74 

.53 

.38 

.23 

.28 

.34 

.22 

.19 

.11 

4.07 

4.69 

4.07 

4. 84 

1.50 

2.21 

1.50 

1.02 

16.84 

.94 

15.61 

1.04 

18.34 

.54 

H. 

Disinte- 
gration 
products. 


Silica  (Si02) 

Alumina  (Al203) 

Ferric  oxid  (Fe203> 

Ferrousoxid  (FeO) 

Manganese  oxid  (M113O4)  — 

Lime(CaO) 

Magnesia  (MgO) 

Potash  (K20) 

Soda(Na20) 

Sulphur  trioxid  (S03) 

Phosphorus  pentoxid  (P2O5) 

Titanic  oxid  (Ti02) 

Combined  water  (H20) 


Per  cent. 

32.00 

35.28 

11.80 

1.53 

.08 

.22 

.14 

.30 

.61 

.70 

.04 

2.13 

15.06 


Samples  A,  B,  E,  and  F  are  the  unaltered  lava,  while  C,  D,  G,  and 
H  are  the  adjacent  weathered  products  or  soil  formed  from  the 
respective  lava  samples.  These  samples  were  taken  by  W.  P.  Kelley 
from  gulches  on  Oahu,  where  large  exposed  lava  bowlders  have 
undergone  weathering  to  such  an  extent  that  samples  may  be  taken 
showing  all  stages  of  disintegration  from  the  unaltered  lava  rock  to 
the  soil.  The  alkalis  and  silica  are  the  most  soluble  constituents, 
and  the  former  are  almost  entirely  leached  away  in  the  process  of 
disintegration.  The  iron  is  rapidly  oxidized  to  the  ferric  condition, 
accompanied  by  a  change  to  red,  yellow,  or  brown  soil,  depending  on 
the  state  of  hydration. 


SELECTION   OF   SOIL  TYPES. 

In  selecting  soils  for  this  investigation,  the  policy  of  selecting  all 
the  more  important  soil  types,  adopted  in  previous  soil  studies  in 
this  laboratory,  was  pursued.  The  impossibility  of  drawing  con- 
clusions from  results  obtained  from  one  type  of  Hawaiian  soil  has 
been  brought  out  in  previous  bulletins  of  this  station.  The  mechan- 
ical and  chemical  composition  of  the  soils  used  are  given  in  the  fol- 
lowing tables : 

Mechanical  analyses  of  the  soils. 


Soil  particles. 

Soil 
No.  164. 

Soil 
No.  291. 

Soil 
No.  292. 

Soil 
No.  339. 

Soil 
No.  392. 

Soil 
No.  428. 

Soil 

No.  448. 

Soil 
No.  474. 

Soil 
No.  547. 

Clay 

Per  cent. 
21.10 
51.70 
19.50 
3.79 

}    ■» 

Per  cent. 

59. 35 

12.13 

7.28 

7.46 

/        .39 

1        0 

Per  cent. 

7.23 
12.41 

8.69 
22.04 
18.75 
20.91 

Per  cent. 
19.19 
22.37 
20.42 
18.13 
.22 
.13 

Per  cent. 
7.87 
19.36 
13.93 
35.  71 
10.22 

Per  cent. 

0.69 

1.76 

5.38 

15.83 

32.82 

13.81 

Per  cent. 
6.85 
20.00 
13.45 
16.31 
8.60 
1.94 

Per  cent. 

5.24 

24.20 

18.00 

30.70 

}      3.43 

Per  cent. 
9.33 

Fine  silt 

35.00 

Silt 

30. 15 

Fine  sand 

10.75 

Coarse  sand 

1.57 

Chemical  composition  of  the  soils. 


Constituents. 


Soil 

Soil 

Soil 

Soil 

Soil 

Soil 

Soil 

Soil 

No.  104. 

No.  291. 

No.  292. 

No.  339. 

No.  392. 

No.  428. 

No.  448. 

No.  474. 

Per  ct. 

Pit  ct. 

Per  ct. 

Per  ct. 

Per  ct. 

Per  ct. 

Per  ct. 

Per  ct. 

1.22 

9. 33 

7.65 

8.90 

5. 51 

14.94 

L6.00 

13.59 

48.11 

41.21 

38.49 

33.75 

29.  (14 

34.99 

15. 10 

33.77 

37.47 

15.89 

16.63 

22.  69 

15.  72 

8.24 

19.20 

7.00 

3.05 

15.39 

12. 85 

11.60 

24.  78 

10.73 

lti.  64 

16.  79 

1.72 

1.25 

2.00 

2.66 

1.80 

3.20 

4.20 

1.80 

.10 

.18 

.24 

.07 

2.26 

.20 

.0(1 

.07 

.12 

.67 

1.84 

.39 

.52 

1.91 

.50 

3.80 

1.22 

1.41 

8.47 

.24 

.50 

2.24 

1.80 

.85 

.48 

.17 

.39 

.13 

.40 

.24 

.15 

.72 

1.46 

.40 

1.36 

.40 

.21 

1.40 

.68 

.10 

.07 

.20 

.57 

.26 

.28 

.22 

.29 

2.78 

.44 

.09 

.08 

.18 

.31 

.45 

.53 

.  45 

3.56 

12.77 

8.42 

19.15 

19.00 

22.  24 

25.58 

20.01 

Soil 
No.  547. 


Moisture 

Insoluble  matter 

Ferric  oxid  ( Fe2C>3) 

Alumina  ( A1203) 

Titanic  oxid  ( Ti02) 

Manganese  oxid  (M113O4) 

Lime(CaO) 

Magnesia  (MgO) 

Potash(K20) 

Soda(Na20) 

Phosphorus  pentoxid  (P2O5) . 

Sulphur  trioxid  (S03) 

Volatile  matter 


Per  ct. 

3.12 
34.  54 
30.84 
10.68 

6.20 


.40 
1.25 

.19 
.13 

.43 

.10 

12.20 


The  above  analyses  were  made  by  extraction  with  hydrochloric 
acid.  On  fusion  with  sodium  carbonate  the  analysis  of  soil  No.  164 
gave  18.9  per  cent  titanic  oxid. 

Soil  No.  164  is  a  peculiar,  fine-grained,  gray,  silty  soil,  evidently  of 
residual  formation.  It  has  an  unusually  high  specific  gravity  (2.8) 
and  resembles  more  a  mineral  deposit  than  a  soil. 

Soil  No.  291  is  very  unlike  the  normal  clay  soils  of  the  islands.  It 
is  brown  in  color  and  is  very  similar  in  physical  properties  to  the 
adobe  soils  of  the  mainland.  Drainage  is  very  poor  and  plowing 
difficult,  and  when  the  soil  dries  it  becomes  almost  as  hard  as  cement. 
It  is  probably  a  transported  soil,  as  it  occurs  in  the  valleys  or  gulches 
extending  back  into  the  mountains. 

No.  292  is  a  sandy  soil  formed  from  the  disintegration  and  decom- 
position of  volcanic  ash.  It  is  highly  productive,  owing  to  its  excel- 
lent physical  and  chemical  composition. 

No.  339,  a  silty  soil  from  windward  Oahu,  is  very  productive  and 
is  devoted  primarily  to  rice  culture. 

No.  392  is  representative  of  the  types  of  red  silty  soils  found  in 
the  islands. 

No.  428,  a  sandy  soil  from  the  Olaa  district  of  Hawaii,  has  been 
formed  from  the  disintegration  of  lava  under  very  humid  conditions, 
and  hence  is  very  high  in  organic  matter. 

No.  448  represents  a  yellow  clay  silt  found  more  or  less  widely  dis- 
tributed throughout  the  islands.  It  contains  a  notably  high  content 
of  combined  moisture. 

Xo.  474  is  a  highly  organic  sandy  silt  from  the  Waimea  district  of 
Hawaii.  It  has  an  extremely  loose  structure,  making  it  very  dusty, 
but  it  is  highly  productive. 

No.  547  was  chosen  as  representing  the  brown  clay  silts  of  the 
islands  and  as  belonging  to  the  class  of  clays  in  which  the  iron  con- 
tent is  greater  than  the  alumina.  There  is  another  class  in  which  the 
alumina  predominates. 


8 

COMPOSITION  OF  THE  SOIL  PARTICLES. 

Analyses  of  the  soil  particles  were  made  by  fusion  with  sodium  car- 
bonate.   The  results  are  given  in  the  following  table: 

Composition  of  the  soil  particles. 

SILICA  CONTENT. 


Soil  particles. 


Clay 

Fine  silt — 

Silt 

Fine  sand . . 
Coarse  sand. 


Soil 

No.  164. 


Per  cent. 

32.70 

30.10 

1.72 

2.33 


Soil 
No.  291. 


Per  cent. 
47.75 
42.80 
35.50 
32.50 
29.90 


Soil 
No.  292. 


Per  cent, 
44.25 
44.75 
38.00 
43.95 
33.25 


Soil 
No.  339. 


Per  cent. 
38. 10 
37.90 
34.50 
31.70 
31.75 


Soil 
No.  392. 


Per  cent. 
32.50 
28.10 
20.60 
25.60 
22.80 


Soil 
No.  428. 


Per  cent. 
20.35 
31.70 
34.30 
38.10 
36.15 


Soil 
No.  448. 


Per  cent. 
12.48 
20.70 
16.30 
19.05 
27.28 


Soil 
No.  474. 


Per  cent, 
34.30 
42. 40 
36.50 
39.40 
33.45 


Soil 
No.  547. 


Per  cent. 

32.10 

24.80 

6.37 

7.36 

10.92 


IRON  CONTENT. 


Clay 

19.21 
15.30 
45.80 
39.25 

15.30 
18.98 
26.60 
32.15 
23.92 

11.53 
13.36 
18.28 
29.05 
17.10 

15.85 
15. 81 
20.90 
30.60 
20.95 

16.80 
16.42 
18.90 
18.92 
18.05 

12.86 
18.05 
16.70 
17.98 
16.60 

25.16 
30.50 
31.60 
24.95 
22.70 

10.01 
9.61 
10.56 
15. 96 
14.96 

22  35 

Fine    silt 

Silt 

23.70 
43.90 

Fine  sand 

41.70 

39  10 

ALUMINA  CONTENT. 


Clay.. 

Fine  silt 

Silt 

Fine  sand . . 
Coarse  sand. 


32.29 
28.95 
13.72 
30.82 


27.53 
26.52 
23.93 

22.48 
33.37 


30.86 
29.51 
26.64 
10.94 
13.60 


40.39 
37.95 
34. 24 
26.05 
34.75 


42.92 
39.05 
40.91 
38.93 
49.13 


47.95 
26.68 
24.16 
20.72 
23.87 


48.42 
36.44 
34.71 
41.14 

20.42 


30.15 
29.60 
32.50 
30.02 
27.26 


32.40 
35.22 
17.19 
30.50 
36.41 


TITANIUM  CONTENT. 


Clay 

8.91 
15.29 
26.50 
21.45 

3.45 
4.72 
6.40 
4.38 
2.99 

3.16 
3.31 
5.47 
5.68 
1.79 

2.92 

4.52 
7.22 
8.37 
2.94 

2.77 
3.70 
5.79 
5.4£ 
3.34 

3.62 
3.89 
5.87 
4.36 
3.35 

4.52 
5.92 
7.48 
7.68 
3.54 

2.19 
2.59 
7.41 
2.21 
3.39 

6.31 

Fine  silt 

10.19 

Silt 

17.23 

Fine  sand 

14.32 

12.01 

PHOSPHORIC  ACID  CONTENT. 


Clay 

0.39 

1.76 

.25 

.68 

0.47 

1.53 

.57 

.66 

.95 

1.70 

2.22 

.81 

.53 

.61 

0.84 

1.02 

.54 

.54 

.61 

0.91 

2.08 

.15 

.41 

.38 

1.32 

1.58 
.67 
.63 
.38 

1.65 

1.74 

.81 

.65 

.56 

4.47 
4.45 
1.83 
1.51 
1.19 

1.24 

Fine  silt 

1.64 

Silt 

.58 

.38 

.88 

MANGANESE  CONTENT. 


Clay 

0.20 
.29 
.60 
.40 

0.54 

.55 

1.30 

.68 
2.60 

0.11 
.39 
.97 
.61 

1.24 

0.04 
.45 
.54 
.41 

1.88 

0.34 
2.43 
3.18 
5.12 
8.75 

0.11 
1.08 
1.41 
.49 
1.17 

0.18 
.31 
.57 
.42 

.68 

0.46 
.53 
.66 
.67 
.95 

0.15 

Fine  silt 

.33 

Silt 

.46 

Fine  sand 

.60 

Coarse  sand 

4.35 

LIME  CONTENT. 


Clav 

0.72 
.96 
.30 

1.04 

1.09 
1.73 

1.47 
3.50 
1.33 

1.56 
3.29 
.83 
1.10 
4.37 

1.11 
.97 
.92 
.98 

1.79 

1.25 
1.63 
1.66 
.90 
1.24 

2.46 
6.43 
5.90 
8.28 
7.63 

1.32 
1.29 
1.13 
2.08 
3.05 

3.04 
6.50 
6.46 
6.77 
6.92 

1.16 

Fine  silt 

.87 

Silt 

.69 

Fine  sand 

1.02 

Coarse  sand 

2.23 

Composition  of  the  soil  particles — Continued. 

MAGNESIA  CONTENT. 


Soil  particles. 


Clay 

Fine  silt — 

Silt 

Fine  sand. . 
Coarse  sand. 


Soil 
No.  164. 


Per  cent. 
0.76 
2.74 
2.05 
2.65 


Soil 
No.  291 


Per  cent. 
0.99 
2.14 
1.59 
2.27 
2.35 


Soil 
No.  292. 


Per  cent 
1.18 
2.73 
3.27 
2.27 
23.49 


Soil 
No.  339. 


Per  cent. 
1.27 
.96 
1.04 
1.26 
3.22 


Soil 
No.  392. 


Per  cent.  Per  cent 


Soil 
No.  428. 


0.85 
1.22 
.95 
1.59 
1.57 


1.67 

5.98 
4.95 
9.18 
10.38 


Soil 
No.  448. 


Soil  Soil 

No.  471.  No.  547. 


Per  cent.  P<r  a  nt. 


0.71 
1.49 
1.21 
3.44 

15.90 


1.02 
1.42 
2.08 
3.11 
5.13 


Pit  cent. 

0.92 
1.55 
2.84 
3.59 
3.03 


Silica. — Generally  silica  is  present  in  larger  amounts  in  the  smaller 
soil  particles.  As  a  general  rule,  it  may  be  said  that  it  is  highest 
in  clay'  and  decreases  with  an  increase  in  the  size  of  the  soil  grains. 
In  the  above  table  there  are  three  exceptions  to  this  rule  and  each 
of  the  three  samples  represents  a  type  geologically  of  far  more  recent 
formation  than  the  other  soils.  Furthermore,  disintegration  is  by 
no  means  complete,  and  silica  being  one  of  the  most  soluble  con- 
stituents of  lava,  it  is  probable  that  these  soils  will  increase  in  silica 
content  as  the  clay  and  silt  content  increases. 

Iron. — This  element  is  present  in  largest  amounts  m  the  silt  and 
fine  sand  particles  and  in  smallest  quantities  in  the  clay.  The  red 
and  brown  clay  silt  loam  have  the  highest  iron  content.  This  is  one 
of  the  most  insoluble  constituents  of  the  lava,  and  its  concentration 
in  the  soil  increases  on  weathering. 

Alumina. — Theoretically,  aluminum  should  be  found  in  largest 
quantities  in  clay,  since  pure  clay  is  an  aluminum  silicate.  This 
holds  for  only  5  of  the  9  types  of  Hawaiian  soil  analyzed.  The 
general  tendency  is  toward  a  relation  similar  to  that  existing  be- 
tween silica  content  and  size  of  soil  particle,  namely,  a  decrease  in 
alumina  content  with  an  increase  in  size  of  particles  up  to  coarse 
sand.  In  the  sand  grains,  the  alumina  content  is  very  high,  in  several 
instances  being  higher  than  in  clay.  It  is  present  in  largest  amounts 
in  the  clay  silts. 

Titanium. — This  element,  while  entirely  inert  toward  plant 
growth,  is  of  considerable  importance  in  Hawaiian  soils.  It  occurs 
mainly  in  silt  and  fine  sand  grains  and  is  least  prevalent  in  clay. 
"When  present  in  abnormal  quantities,  titanium  is  invariably  asso- 
ciated with  a  high  iron  content  and  better  soil  texture  than  that 
of  other  red  clay  silts. 

Phosphoric  acid. — This  is  present  in  largest  amount  in  clay  and 
fine  silt  particles.  This  fact  probably  explains  the  extremely  non- 
available  condition  in  which  phosphates  exist  in  Hawaiian  soils  and 
supports  the  contention  in  previous  publications  of  this  station  that 
the  nonavailable  properties  of  phosphates  in  local  soils  are  due  in 


10 

large  part  to  the  physical  influence  of  the  clay,  in  so  far  as  it  governs 
the  concentration  and  composition  of  the  soil  solution.1 

Manganese. — The  manganese  content  of  the  grains  apparently  in- 
creases with  the  size  of  the  soil  particles.  Only  traces  of  this  element 
are  found  in  clay,  while  appreciable  amounts  are  present  in  coarse 
sand.  It  may  be  mentioned  in  this  connection  that  a  soil  of  high 
manganese  content  always  possesses  a  loose,  sandy  texture,  although 
it  may  be  surrounded  on  all  sides  by  heavy  clay  types. 

Lime. — While  lime  is  found  in  appreciable  amounts  in  clay  par- 
ticles, a  result  to  be  expected  from  its  general  properties,  it  is  present 
in  largest  amount  in  the  coarse  grains.  Lime  is  an  extremely  variable 
constituent  in  Hawaiian  soils,  and  its  presence  or  absence  is  in- 
fluenced to  a  marked  degree  by  weathering  agents. 

Magnesia. — Magnesia,  being  similar  to  lime  in  most  of  its  prop- 
erties, is  found  distributed  in  the  soil  grains  with  relation  to  size 
very  much  in  the  same  way  as  lime.  Hawaiian  soils  are  almost 
uniformly  higher  in  magnesia  than  in  lime.  Lime  is  apparently 
present  in  larger  amounts  than  magnesia  in  the  clay  particles. 

PROPERTIES  OF  THE  SOIL  PARTICLES. 

Coarse  sand. — Under  this  head  are  classed  all  particles  from  0.2 
to  1  millimeter  in  diameter.  It  might  be  expected  that  these  particles 
would  more  closely  resemble  lava  in  composition,  since  disintegra- 
tion has  not  progressed  far,  but  in  most  cases  leaching  has  been  so 
complete  that  there  is  little  difference  in  composition  whether  the 
soil  is  derived  from  volcanic  ash  or  lava.  Soil  No.  291  is  a  trans- 
ported type  derived  from  volcanic  ash,  and  the  sand  grains  seem  to 
be  composed  primarily  of  a  complex  magnesium  silicate.  No.  292 
is  a  soil  derived  from  the  same  ash  but  through  the  action  of  differ- 
ent weathering  agents. 

Fine  sand. — This  division  includes  all  grains  ranging  in  size  from 
0.04  to  0.2  millimeter  in -diameter.  In  passing  from  coarse  to  fine 
sand,  the  soil  particles  show  a  tendency  toward  an  increase  in  silica, 
titanium,  and  iron,  and  a  decrease  in  alumina.  In  certain  types  in 
which  titanium  is  abundant,  silica  is  present  in  very  small  amounts 
in  the  coarse  particles. 

Silt. — The  next  division  consists  of  particles  ranging  in  size  from 
0.01  to  0.04  millimeter  in  diameter.  In  passing  from  fine  sand  to  silt 
there  is  a  further  increase  in  silica  content,  while  the  iron  and  alumina 
present  no  uniform  change,  some  samples  showing  an  increase  in 
these  constituents,  others  a  decrease. 

Fine  silt. — These  particles  vary  in  size  from  0.002  to  0.01  millimeter 
in  diameter.    The  silica  content  varies  from  20.70  to  44.75  per  cent, 

i  Hawaii  Sta.  Buls.  35   (1914),  38  (1915),  40  (1915). 


11 

the  iron  from  9.61  to  30.50,  and  the  alumina  from  26.52  to  39.05  per 
cent.  As  compared  with  silt  and  coarser  particles,  fine  silt  is  higher 
in  silica  and  alumina  and  lower  in  iron. 

Clay. — The  smallest  grains,  0.002  millimeter  or  less  in  diameter,  in 
Hawaiian  soils  are  referred  to  as  clay  only  in  so  far  as  this  term  ap- 
plies to  the  size  of  the  soil  particles.  Grains  taken  from  a  red  clay 
soil  showed  diameters  ranging  from  0.00165  to  0.00065  millimeter. 
As  regards  the  composition  of  Hawaiian  clay,  silica  varies  from  12.48 
to  47.75  per  cent,  ferric  oxid  from  10.01  to  25.16  per  cent,  and  alumina 
from  27.53  to  48.42  per  cent.  With  the  exception  of  titanium,  the 
other  constituents  do  not  vary  greatly. 

The  colors  of  the  clay  samples  were  red,  yellow,  and  brown,  the 
depth  of  each  color  varying  considerably.  The  yellow  clays  were 
lowest  in  iron  and  contained  the  least  combined  water.  This  latter 
fact  does  not  necessarily  hold  for  yellow  soils.  The  clay  separated 
from  soil  No.  448,  a  yellow  type,  had  a  red  color  before  ignition.  All 
clays  had  the  same  depth  of  redness  after  ignition. 

The  properties  of  these  clays  vary  as  widely  as  their  composition. 
Soil  Xo.  291,  the  highest  in  silica,  was  as  hard  and  brittle  as  cement 
upon  drying.  The  other  clays  all  remained  in  the  form  of  a  fine 
powder  on  ignition.  The  most  noticeable  of  the  peculiar  properties 
of  these  clays  is  the  action  toward  coagulants.  Analyses  of  the  co- 
agulable  and  noncoagulable  grains  are  submitted  herewith.  Four 
samples  of  soil  were  treated  according  to  the  official  method  for  de- 
termining humus.  Treatment  with  ammonium  carbonate  of  the 
humus  extract,  which  contained  large  amounts  of  clay,  resulted  in  a 
partial  coagulation.    The  results  are  given  in  the  following  table : 

Composition  of  clay  coagulated  and  not  coagulated  from  the  humus  extract  by 

ammonium  carbonate. 


Coagulated. 

Not  coagulated. 

Constituents. 

Soil 
No.  99. 

Soil 
No.  101. 

Soil 
No.  106. 

Soil 
No.  108. 

Soil 
No.  99. 

Soil 
No.  101. 

Soil 
No.  106. 

Silica 

Per  cent. 
29.00 
37.38 
33.12 

Pa  cent. 
22.24 
34.93 
37.33 

Per  cent. 
25.33 
34.91 
30.42 

Per  cent. 
23.80 
37.84 
31.16 

Per  cent. 
38.21 
23.40 
37.39 

Per  cent. 
38.29 
18.14 
43.57 

Per  cent. 
46.01 

Alumina 

21.42 

Ferric  oxid 

32.57 

Some  Hawaiian  clays  are  almost  completely  coagulated  by  am- 
monium carbonate  but  it  appears  that  the  action  of  this  salt  is  greatly 
inhibited  in  clays  high  in  iron  and  silica,  but  low  in  alumina.  The 
clay  in  soil  Xo.  108  was  entirely  coagulated,  hence  only  analysis  of 
coagulated  grains  is  tabulated. 

As  regards  the  relation  between  the  composition  of  the  clay  and 
coarser  grains,  silica  and  alumina  vary  between  wider  limits  than  in 
the  silts.    The  clay  also  contains  the  highest  silica  content. 


12 

CONCLUSIONS. 

(1)  There  is  a  wide  variation  in  the  composition  of  soil  particles 
of  the  same  size. from  different  soil  types  in  Hawaii. 

(2)  This  variation  is  due  primarily  to  the  number  and  intensity 
of  action  of  the  several  weathering  agents  which  are  instrumental 
in  the  disintegration  of  the  lava. 

(3)  Iron,  titanium,  and  manganese  are  present  in  largest  amount 
in  the  coarse  grains.  Silica,  alumina,  and  phosphoric  acid  predomi- 
nate in  the  finest  particles,  lime  and  magnesia  in  the  coarse  grains. 

(4)  The  influence  of  coagulants  upon  Hawaiian  clays  varies  with 
the  composition  of  the  clay.  Those  most  difficultly  coagulable  are 
higher  in  iron  and  silica  than  those  readily  coagulable. 


LIST  OF  PREVIOUS  STATION  PUBLICATIONS  ON  HAWAIIAN  SOILS. 

BULLETINS. 

No.  26.  The  Function  and  Distribution  of  Manganese  in  Plants  and  Soils. 

No.  28.  The  Effect  of  Manganese  on  Pineapple  Plants,  and  The  Ripening  of  the 

Pineapple  Fruit. 
No.  30.  The  Effect  of  Heat  on  Hawaiian  Soils. 

No.  31.  Rice  Soils  of  Hawaii :  Their  Fertilization  and  Management. 
No.  33.  The  Organic  Nitrogen  of  Hawaiian  Soils. 
No.  35.  Absorption  of  Fertilizer  Salts  by  Hawaiian  Soils. 
No.  37.  Ammonification  and  Nitrification  in  Hawaiian  Soils. 
No.  38.  Effect  of  Fertilizers  on  the  Physical  Properties  of  Hawaiian  Soils. 
No.  39.  The  Biochemical  Decomposition  of  Nitrogenous  Substances  in  Soils. 
No.  40.  The  Soils  of  the  Hawaiian  Islands. 
No.  41.  Phosphate  Fertilizers  for  Hawaiian  Soils,  and  Their  Availability. 

PRESS  BULLETINS. 

No.  23.  The  Influence  of  Manganese  on  the  Growth  of  Pineapples. 

No.  29.  The  Management  of  Pineapple  Soils. 

No.  33.  A  Study  of  Humus  in  Hawaiian  Soils. 

No.  38.  The  Use  of  Dynamite  in  Farming. 

No.  50.  The  Effect  of  Arsenite  of  Soda  on  the  Soil. 


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